Use of force to prevent self harm

18 October 2021

Not reviewed after the date of publication


We know from common law that a reasonable and proportionate amount of force may be used to defend yourself or another. Is this considered the most appropriate use of force power to protect a person who intends or states they are going to self-harm and force is required to stop them hurting or killing themselves? Is there any other legislation that can be used here?


Depending on the situation, there are a number of powers available to officers to protect a person from serious harm to themselves or others. When officers are dealing with individuals suffering from mental health concerns and physical intervention becomes necessary, the most appropriate legislative power will depend on the specific circumstances, however the powers contained Mental Health Act 1983 and Mental Capacity Act 2005 are likely to be most appropriate.

Section 136 of the Mental Health Act 1983, provides for the police to take a person believed to be suffering from a mental disorder from a public place to a place of safety. The detention or removal of a person under this section is a preserved power of arrest under Schedule 2 PACE and therefore, officers may use reasonable force under section 117 of PACE. However, officers should not use methods of restraint on people with mental ill health or vulnerabilities, unless absolutely necessary. They should reserve this for emergencies and circumstances in which the safety of the subject, the public, police officers and other professionals is at risk. Please see the College of Policing guidance on mental health and detention, which includes a section on restraint:

The above link provides a summary of the sources of the power to use reasonable force and some case law. Ultimately a constable must be able to justify any use of force in the circumstances.

When using section 136 of the Mental Health Act 1983, in order to achieve the desired outcome of removing the person concerned to a place of safety, paragraph 16.24 of the Mental Health Act 1983: Code of Practice states:

"16.24 The use of physical restraint or force may be required when removing a person, or in a place of safety, for the protection of the person or others (such as the public, staff or patients). If physical restraint is used, it should be necessary and unavoidable to prevent harm to the person or others, and be proportionate to the risk of harm if restraint was not used. The least restrictive type of restraint should be used. There should be a clear local protocol about the circumstances when, very exceptionally, police may be asked to use physical restraint in a health-based place of safety. For definitions of restraint and guidance on the use of restraint in hospital see chapter 26."

Both legislative provisions require that any use of force should be 'reasonable' in the circumstances. Reasonable in these circumstances means absolutely necessary for a purpose permitted by law, the amount of force used must also be reasonable and proportionate (i.e., the degree of force used must be the minimum required in the circumstances to achieve the lawful objective) otherwise, it is likely that the use of force will be excessive and unlawful. This is synonymous to the requirements of the Mental Health Act Code of Practice. Excessive use of force is unlawful.

Under the Mental Capacity Act, a person (including a police officer) can undertake an act in connection with the care or treatment of another person, if they reasonably believe that the person lacks capacity and the relevant act it is in his best interests. A person can be deprived of their liberty (for example, by the police) and / or force may be used, but only if it is to enable life-sustaining treatment or treatment necessary to prevent a serious deterioration in the person's condition.

Please be aware of the case of ZH v Commissioner of Police for the Metropolis (2012), where it was held that where the provisions of the Mental Capacity Act apply to a matter, the common law defence of necessity and accompanying use of force would not be available. Where the provisions of the Act did not apply, the common law defence of necessity and any requisite force arising out of reliance on that, may be justified, the usual requirements of force being necessary, reasonable and proportionate must still be considered. The same point was previously made in the case of Sessay (2011) with regards to the relationship between necessity and the Mental Health Act 1983.

Where a person is not in a public place then it may be that the provisions of section 17(1)(e) of PACE would be appropriate to use whereby a constable may enter and search any premises for the purpose of saving life or limb. As a PACE power, it would also come under the remit of section 117 of PACE for the use reasonable force in the exercise of the power. However, please be award of the case of Syed v DPP 2010 which held that concern for welfare is too low a threshhold to force entry under s17(1)(e) of PACE. There would therefore need to be a serious threat of harm to the person concerned to justify such an entry for these purposes.

If there is a question as to whether excessive force was used, there is a test laid down which determines the matter (it principally applies to self-defence but, similarly, can be applied in determining whether excessive force was used under either of these provisions). In R v Owino 1996 and confirmed in DPP v Armstrong-Braun 1998, the defined test was:

"A jury must decide whether a defendant honestly believed that the circumstances were such as required him to use force to defend himself from an attack or threatened attack the jury has then to decide whether the force used was reasonable in the circumstances."

Please note that this is basically an 'objective' test determined by the jury. They do not have to consider whether the defendant thought his/her actions were reasonable in the circumstances. They just have to consider what the defendant genuinely believed was reasonable.

The College of Police provide guidance on the use of reasonable force and mental health, please see the links below:

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